Howard Coleman

iTrader: (6)

i recently received an extremely interesting email from Richard Green.
(Greenbrothers.com.NZ).

Richard and i have corresponded as he runs a similar ECU on his Mazda 323 (rear wheel drive), has a significant rotary shop in New Zealand, and is often on the cutting edge.

in addition, he is the type of guy that shares. here's to you Richard

Richard may be on to something that is important. something that many on this board may find relevant. i asked him if he wanted to do a thread on it and he indicated he would prefer that i would initiate it. so w Richard's assent here goes.

before starting, a couple of qualifications... Richard's conclusions are an opinion. he may be right, he may be wrong. further, perhaps this all may have been discussed somewhere on the board but after doing some searching i am confident that many reading this will find it fresh and possibly valuable.

finally, this sure isn't the last word on the subject and i, as always, welcome all points of view.

brief background as to what Richard is up to...

drag racing
dual purpose Mazda 323 rear wheel drive wagon 2309 pounds (street/drag strip)
BW 475
pump gas
uses water/meth 50/50
Link ECU
i believe he has been running in the low 9s close to 150 w slicks

Richard asks that Brent @ Dynopower be given props. he runs the dyno and the earphones...

during the last part of December Richard decided to do some comparative work with his ignition system.

test one
ICE coils w Microtec X4 igniter (inductive)
increased voltage from 16 to 24 V at the coils and reduced dwell
doubled the amount of WM to near 2000 CC/Min
@30 psi misfired at peak torque
added dwell, fried (he thought) the X4

test two
removed his ICE coils/X4 and substituted AEM Smart Coils
was able to run 34 psi w 2000 cc WM
slight misfire at peak RPM

reduced spark duration to .8 mS from 1.5 mS
reduced V to coil to 16V
better but still some peak misfire
640 hp

test three
added Motec Pro14r CDI (M&W)

so run three didn't change from two other than he switched from
inductive to CDI

power the same as two til peak torque, then dropped 20-30 hp to redline

decided to change the plug gap so pulled the plugs and found that he had neglected to swap in his race plugs for ALL of the above runs. the motor had
BUR9 plugs!

test four
swapped in race plugs (fine wire 6725) gapped at .25
motor gained 20-30 hp after peak torque so back to 640

test five
swapped out the CDI so went back to inductive
gained 40 hp to 680 but had slight misfire in higher rpm range

Richard uses the Link KnockBlock and a pair of earphones while on the dyno. apparently the earphones work well and allow him to be anticipatory re the state of knock.

given the events, Richard concludes that the lengthened conduction of current from the inductive setup along w the reduced mass of the finer wire plug grounding strap and center electrode was causing them to become glow plugs and therefore pre-detonation.

the smaller mass 6725 plugs work fine w a CDI setup as you don't have a lengthy heat transfer event.

granted this is all happening at power levels (above 600) than many of us, including me, won't see, however that doesn't mean it isn't relevant. there are many things that effect CCP, not just X power level, and i for one want to have all contingencies covered.

back to Richard...

test six
swapped out race plugs for BR10ES. 655 hp on same boost but more timing. when he increased the boost, "things didn't seem right." looked at plugs and the electrodes were "burning away."

test seven
tried EGV plugs and had pre-ignition immediately.

test eight
BUR (!) plugs, significantly less pre-ignition, made 740 unsafely, barely controlled pre-ignition

decided to go racing w ES and a conservative tune...

here's Richard's report from the track...

"And then the wastegate started playing up and we'd run out of time so we went racing today with the es plugs and a basic tune, hoping for the best with the wastegate. It wasn't a good day temp and traction wise but we still ran real close to a pb and almost 3mph more, and that's with an extra 130lb weight in the car. And we couldn't quite run full boost. 9.1 at 153.4 mph it was. Full street trim apart from slicks.

Anyway, these NASCAR plugs sound like they could be what we need, depending on center electrode diam. Are you able to find out this diam and the gap? And if they do a resistored version? The bur's are good I think, only the gap is a bit too big and the center electrode a little to thin. And they are prob not cold enough."

NASCAR plugs?

enter Lance Nist perhaps better known on the EFI101 board as Pantera EFI. Lance is Mr Amazing. i am always taking notes when we talk as some of it always zips right over my head. Lance is the primary reason i decided to change my ignition system out. i will say my CDI setup never ever let me down but hey let's try something new...

the primary reason for this post is that a number of people have, or are, discovering the Mercury Coil (MC) along w the many re-badged iterations.
many have been running the $30 plugs w their previous setups. if Richard is correct, a combo of the MC and low mass electrodes could lead to pre-ignition and you all know where that leads.

so Lance is my go to ignition guy and since he is ALWAYS interested in finding answers i ran all of Richard's situation and theory by him. Lance absolutely agreed. further, he suggested a higher mass plug.

the AR3932X

he referred to it as the NASCAR plug indicating that it was a primary plug in the Sprint Cup.

it does come in heat ranges from 8 to 11 although i have yet to find the 11. i have a few sets in 10 and 9 that should arrive monday.

i have been aware of the AR3932 plug and have actually used it a bit but not on the dyno or track. it is an Autolite Racing plug w a stout single ground strap. nothing fancy materials-wise.... nickel.

the "X" is a different animal. it has FOUR ground staps.... sort of like the BUR...



whether the plug is the "answer" to the specific needs of a very strong inductive setup or not will of course need to be determined. i did a search on this board and FWIW didn't find any mention of the plug.

no doubt much of all the above will not be news to many operating in the 600 and above stratosphere OTOH, due to the kindness of Richard Green as to sharing, the concept is now "out there."

there are quite simple ignition setups that have been proven to work well at 500 hp power levels so for those that have these systems this all is perhaps just not that valuable. lots of simple stuff works.

for those inclined to be more venturous this is extremely interesting. let's see where this leads.

thanks, again Richard, and thanks Lance.

howard

mono4lamar

iTrader: (32)

I have these that I'm waiting to use once I get some dyno time lined up. No ground strap to break off and gapless. I can get them from 9,10,11,12 and overkill 15. The next option is the ngk 6252's but I think they'll be too cold.

Neutron

iTrader: (10)

Subscribed.

jantore

Verry good info Howard. Richard is a good man for sharing this. And he is quite well knowledged. Greenbrothers is where i sourced my 4 rotor parts from.

Do you know if the AR3932X plugs will work on a CDI setup as well? As im running Autronic CDI + Crane Cam coils?

Changing to MC coils is not a big deal, but if the Autolite plugs work on the CDI setup then that should do fine

Very interesting read thoug about the difrent plugs.

JT

bumpstart

http://www.stoneskartsport.com.au/Ar...2029.10.12.pdf
...check batches ...
also maybe confirm if the test was always BR10ES ( nickel ) . or B10ES ( copper )
as the copper will always make least resistance and quench fastest at the tip.. , plug for plug,, ...new ..
the question is will the large soft tip retain its properties and advantage over time...

i believe the fine wire tips use precious metals for anti wear characteristics and a fine ground tip to improve the conductivity
..they stay more consistent in gap over life and are inherently less prone to fouling deposits

fine tip plugs have had there issues.. the recall above is for EGV
.. though i havent had a problem in the past and had already moved to EG for economy reasons anyhows
-EG is also nickel ( but fine tip )

Bacon

iTrader: (12)

Although it would seem he only made 2 pulls on the 6725's did he have any cracks in the ceramic insulators? We have seen them get hairline equidistant cracks in the ceramics, wondering if his hypothesis on the latent heat has alot to do with this.
great thread!

Howard Coleman

iTrader: (6)

BTW, here's Richard's thread, four really good pages... enjoy

https://www.rx7club.com/auxiliary-in...rbo-wi-974884/

i will check re the specific condition of the 6725s

as to whether the AR3932X would work w CDI... i have no special knowledge here other than i know the 6725s work w the CDI.

my guess is that "mass" is the key.

mass as in center electrode
mass as in the elec grounding strap
and most importantly, mass as in current. as in the total number of electrons making the trip to ground.

i have read that the finer wire plug presents a sharper launch for the spark and in some cases this could be the make or break..
i think you would just have to experiment. the plugs are around $6 so as long as you don't hurt the motor it would be a difficult deal.

howard

thewird

iTrader: (8)

How exactly was the spark duration reduced when you have no control over that since the inductive coils just fire when you ground the coil? Do you mean he reduced the dwell to provide a shorter duration? The Microtech only allows a for a primitive fixed dwell setting (either time or duty cycle based).

Why doesn't he just add more injection if hes getting pre-detonation? He's pushing the limits of pump gas, he needs less of that fuel in there or more of the other lol.

On a side note, I've seen those Autolites break in other peoples motors causing engine damage. Could just be a coincidence but just thought I'd bring it up.

And some food for thought, tell him to try disconnecting the trailing coils and try his tests again.

Also curious what kind of timing he is running at those boost levels vs when the spark plugs become exposed to the raw fuel. Basically when he wants it to fire vs when its supposedly pre-detonating.

thewird

JZG

Firstly, many thanks to Howard for putting this info up as I simply do not have the time, and it's more credible coming from him anyway. What started as a quick warning to Howard about the inductive/race plug anomaly I found by accident, turned into a full blown discussion that I think some rotary owners can benefit from.

JT - Thanks for the kind words. I don't think you'll have a problem with the CDI and race plugs because the spark duration is so short which = less heat in the plug electrodes. However over 650hp on pump gas may be a different story as there will inherently be more combustion heat. If you can run the race plugs with no problem then they will make more power, last longer, and be less prone to fouling.

Bumpstart - the plugs were BR10ES not B10ES. Can you still buy EG plugs? They seem to be superseded here in NZ.

Bacon - the race plugs looked good. They were new and there were no cracks or damage or odd marks/colours. To be fair they weren't in there for long. R4720-10 leading and R6725-11 trailing

thewired - I'm using a Link computer and contrary to Microtech I can actually adjust most parameters. The spark duration number is the minimum amount of time the ecu lets the coil discharge for before it starts charging again. This only comes into play when dwell + spark duration are equal to or longer than the time available for this cycle to complete - e.g higher rpms. And it was over 8500rpm where the difference was noticed in this case. Even though there are 6.6ms available at 9000rpm, and 5ms dwell + 1.5ms spark duration = only 6.5ms, I believe the coil needs a small amount of ms between discharging and charging. Hence the gain when duration was reduced to .8ms. Most good coils take at least 1.5ms to discharge which means the spark burns for 1.5ms giving good re-strike opportunity. As opposed to CDI coil discharge which is typically closer to .1ms I believe, giving no re-strike time (the spark is more intense however).

I tried adding more water - no change

I disconnected the trailing plugs - less pre ignition and a lot less power, but it shows the trailing plugs have something to do with the pre-ignition.

About 4 deg at peak torque and about 12deg at peak rpm from memory

thewird

iTrader: (8)

Hmm, I wonder if your affecting actual timing with that setting. A coil is a very simple device, it has 2 states, CHARGE and DISCHARGE. CHARGE is the controlled event by the computer and is done via the dwell setting. DISCHARGE is the point between the charging phase in which the coil fires and then rests after its discharged its energy until the charge phase is triggered again. Now if the computer is trying to control the duration of the spark, it might be shifting when the actual spark event happens. Is there instead of a way to have a fixed dwell that gets reduced when it can't achieve that dwell time.......

OK, I just thought of something, that setting is probably reducing dwell time to maintain the discharge cycle time but didn't want to start the post over lol. So I just Italics it. Can you instead turn that "minimum spark duration" setting off or set it to 0 instead. And then you can play with dwell directly instead of having a modifier in there? Have you tried using different dwell settings? It sounds like your pushing the coils to their extreme and may be just be running out of spark energy which is causing the misfires? The AEM coils are hot stuff but they still only provide ~110 mj of spark energy. There is much stronger stuff out there. Your Pro Drag M&W CDI box provides 250 mj of spark energy if my memory serves me. That is more then double the spark energy and will burnout plugs prematurely lol. It's ment for drag racing lol.

I know ErnieT tried the AEM coils a while back and said he was burning out coils to get the power he needed so they were no good for him. Though, he runs straight race fuel I believe. His car makes over 800 rwhp on a semi-pp motor.

Hmm, the peak torque timing makes sense but thats a lot of timing at redline for that boost. What kind of porting is done to your motor? Is there any particular RPM where more pre-ignition was happening? It sounded like your issue was all up top? Any dyno plots out of curiosity? I like stuff like this but like seeing full information as it helps understand it better.

thewird

C. Ludwig

iTrader: (27)

There is no such thing as pre-detonation. There is pre-ignition and detonation (or knock). Pre-ignition can't be heard with knock detection equipment. If Mr. Green is hearing something, it's detontaion. That could certainly be what caused the damage to the spark plug. That said, pre-ignition (effectively, uncontrolled spark advance) can lead to detonation.

ErnieT lost one coil at a unknown (to him) duty cycle and dwell.

Spark break time, as described by JZG, will not lead to uncontrolled ignition advance, just less dwell. Spark instant is still controlled by the ECU and initiated when the charge cycle is stopped. Adjusting break time only moves the point at which the charge cycle starts.

JZG

mono4lamar are you able to measure the center electrode diameter and the spark gap on those Bosch plugs? Do you have a part num for them? The pic isn't very clear.

Does anyone have an NGK BUE plug they can measure the electrode diam and gap from?

Once I collect a few more suitable looking plugs I'll be heading back to the dyno. Brisk make some interesting looking plugs also.

Howard Coleman

iTrader: (6)

my Autolite AR3932X plugs arrived today. straight from Autolite in Mich thru NAPA

they may or may not be the plug for a big inductive ignition but they are very different from my 6725s that worked well when i ran CDI.

the center electrode is .095" or 2.43 mm. the electrode grounds are NOT welded and are part of the plug body. beefy and not a possible failure point. gap is approx 30





center electrode on the 6725 is a point. ground strap is approx .9 mm



i have the 3932X 10 heat range and the 3933X 9 heat range. the plugs will head up to Green Bay/Beyond Redline tomorrow.

hc

Bacon

iTrader: (12)

thats a beefy plug! I like it!

BLUE TII

iTrader: (9)

I didn't see it mentioned in this thread but when I looked at the AR3932X on sparkplugs dot com ($4.80)-

it lists the AR3932X as 5/8" hex and kindly lists a 5/8" sparkplug socket under related items.

-edit- ebay has 48 for $133 ($2.77ea) lets hope these work well as my car eats leading plugs.

jantore

I will most likely be running these plugs on the 4 rotor with MC coils in the future. As they are quite cheap compeard to the NGK Iridium plugs, and the 4 rotor eats plugs :P

Im looking forward to more results from this.

JT

afawaterpolo

iTrader: (7)

This is very interesting as I'm running a full bridge 13B-Rew with a lot of mods and have not had any ignition or detonation issues. i am frankly shocked because i was expecting some sort of issue since everyone i talked to said i would. Only thing i can think of is that I'm not running a whole lot of boost and maybe that is why I'm having zero issues. We are planning on turing up the boost to try and hit 900-1000 RWHP on E85 alone. For this reason i am interested in this thread and everyones input as we are looking at raising the boost up in the 32-42 pound range.

Some info on What we are running in the FD is a Motec M84 with an M&W ignition and using the Honda CBR 600 coils (coil on plug). The engine runs from 1800 RPM- 10,500 RPM with zero ignition break up or detonation.

For fuel we are only running E85 sprayed though 6 injectors with a duty cycle of 70% on our 703 RWHP run. All tuning was done by George Marinov and tuned on Steve Kans Mustang dyno.

We had about 2000 miles running stock 9's all around and made 675 RWHP reving to 10,500 RPM at 23 psi with zero ignition or detonation issues.

We then swapped out the plugs for some R6725-115 and were able to hit 703 RWHP at 23 psi. We've been running this set-up for a little over 4000 miles with zero issues.

I'll see what happens as we crank the boost up and add anything in this thread if we start seeing anything funny.

mono4lamar

iTrader: (32)

I've been very busy unfortunately so I haven't had a chance to play with the plugs. Sorry for not PM'ing you back Howard, again I've just been too busy working to do the "play time" end of things.

I'll see what I can do in the next week but I have to pack up my car with parts and get ready to hit the road in the AM to tune three FD's (even though I'm labeled as an aggressive bad tuner ). I still need to confirm some details with the plugs before I recommend anyone wasting their money on them.

I think I actually have a two sets of BUE's I ordered for huha's. I still think after speaking with a rep that they might be too cold for most setups but as long as they don't have issues fouling out often they might prove worthy in the end as far as being cost effective.

Howard Coleman

iTrader: (6)

"Motec M84 with an M&W ignition"

assuming it is the M&W CDI you are probably in excellent shape w the fine wire plug.

Inductive (non-CDI) is significantly different and the long spark duration, around 2,900 microseconds V CDI at 600 microseconds puts a different stress on the electrode. perhaps it turns it into a glow plug which could cause pre-ignition. (not good) perhaps it could erode the electrode. (also not good)

congrats on what you have accomplished to date and good luck going forward.

Howard

afawaterpolo

iTrader: (7)

Howard,

Thanks, I'm extremely curious to see how the autolite ar3932x plugs work compared to the other plugs already discussed in the thread. They seem like a better option construction and price wise.

Looking forward to seeing what you all find with these as I'm always looking to try something new especially in this power area.

JZG

I have ordered some of the Autolite plugs Howard suggested and I will most likely try some BUE plugs at the same time (next dyno session). At the moment the Autolite plugs tick all the right boxes. Cutting back the earth electrode and bending it down to form a side gap is a possible option with the ES plug also.

indio84

iTrader: (7)

Sub

JZG

After a little more testing I have found that the BUE plugs work well in our application. We are now up to 740rwhp reliable at 38psi. It seems the more hp made the more basic the plug wants to be. The ES plugs were working just fine until this last 40hp or so, then pre-ign returned - due to higher combustion temps no doubt. Swapping to BUE's eliminated pre-ign. Even with the BUE's 60 thou gap there is no sign of misfire and the engine runs as clean as it ever has. However after about 8 dyno pulls one of the leading BUE's went bad and because I only had 4 of them I decided to swap 2 of the NASCAR plugs into the leading. Again, the engine pulled clean with no pre-ign and a little more hp was made (the 740hp). But once I removed the BUE's from the trailing and fitted NASCAR plugs pre-ign was back again. It seems the 10 heat range NASCAR plugs (NGK heat range) are too hot for the trailing. I'm going to try some SD11A's next I think.

Anyway, yesterday the car ran an 8.86@154.7mph and an 8.92, 8.96 so we're happy with that. And it's 100% reliable and real low maintenance. At the previous meeting (less hp) it ran 6 or 7 9.0's in a row and we were turning it around quick, only 15min between passes. I'm confident we could drive the car 2 hours to the track, run high 8's all day, and drive home again with no issues.

BTW, this spark plug info most likely only applies to high hp pump fuel - 600hp plus. Under that you can pretty much run any plug you like I suspect. ES plugs work fine and they are about as cheap as you can get.

C. Ludwig

iTrader: (27)

How do you know you're getting pre-ignition?

JZG

The engine sounds like it gets a slight misfire (usually at peak torque or just after) and I can feel a vibration through the car. Boost increases slightly at the same time and if the dyno pull isn't aborted quickly the pre-ignition turns into detonation. Swap the plugs for something with thicker electrodes (or no electrodes) and the pre-ignition goes away, engine sounds good, and boost is normal.

Outright detonation is a different story. There is usually little or no warning before it occurs.